Electronic device

ABSTRACT

An electronic device includes a semiconductor substrate, an electronic element mounted on the substrate, a conductive layer electrically connected to the electronic element, a sealing resin and a columnar conductor. The substrate has a recess formed in its obverse surface. The electronic element is mounted on the bottom surface of the recess. The conductive layer has an obverse-surface contacting region located on the obverse surface of the substrate. The sealing resin is disposed in at least a part of the recess for covering at least a part of the obverse surface of the substrate. The columnar conductor is electrically connected to the obverse-surface contacting region of the conductive layer and exposed from the sealing resin at a side opposite to the obverse surface of the substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to electronic devices.

2. Description of Related Art

Various types of electronic devices have been proposed that performspecific functions in response to external input and output of electriccurrent. To be able to carry out its function, a typical electronicdevice includes a plurality of electronic elements that constitute partof electronic circuits. Metal leads are used to provide structuralsupport for the electronic elements and electrical connection betweenthe electronic elements. The number, shape, and size of the leads aredetermined in accordance with the function, shape, and size of theelectronic elements. The electronic elements mounted on the leads areencapsulated in a sealing resin. The sealing resin is provided toprotect the electronic elements and part of the leads. To be ready foruse, the electronic device is mounted on for example a circuit board ofan electronic instrument. For such electronic devices, appropriateprotection of the electronic elements is important. Documents related toconventional electronic devices include JP-A-2012-99673.

SUMMARY OF THE INVENTION

The present invention has been proposed in view of the abovecircumstances, and an object thereof is to provide an electronic devicethat allows for greater design flexibility in terms of overall size,without compromising protection of electronic elements incorporated.

According to an aspect of the present invention, there is provided anelectronic device that includes: a substrate made of a semiconductormaterial and having a substrate obverse surface and a substrate reversesurface that are opposite to each other in a thickness direction of thesubstrate; an electronic element mounted on the substrate; a conductivelayer electrically connected to the electronic element; a sealing resin;and a columnar conductor. The substrate is formed with anelement-receiving recess recessed from the substrate obverse surface andhaving a recess bottom surface. The electronic element is mounted on therecess bottom surface. The conductive layer has an obverse-surfacecontacting region located on the substrate obverse surface. The sealingresin is disposed in at least a part of the element-receiving recess andalso covers at least a part of the substrate obverse surface. Thecolumnar conductor is electrically connected to the obverse-surfacecontacting region of the conductive layer and exposed from the sealingresin at a side opposite to the substrate obverse surface.

With the above arrangements, the sealing resin and columnar conductorcan be made to protrude by a desired amount with respect to the obversesurface of the substrate. Hence, the overall size of the electronicdevice (in particular, the thickness) can be easily adjusted to meetvarious user's requests by altering the protrusion amount of theabove-noted two members. While such an adjustment for the sealing resinand the columnar conductor is possible, it is not necessary to change,for example, the size of the element-receiving recess and/or thearrangement of the electronic element incorporated, which is veryconvenient for the manufacturer to produce the electronic devicesrequired by the users.

Further features and advantages of the present invention will becomeapparent from the detailed description given below with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an electronic device according to a firstembodiment of the present invention.

FIG. 2 is a cross-sectional view along line II-II in FIG. 1.

FIG. 3 is a cross-sectional view along line III-III in FIG. 1.

FIG. 4 is a cross-sectional view illustrating an example of a method formanufacturing the electronic device shown in FIG. 1.

FIG. 5 is a cross-sectional view illustrating the example of the methodfor manufacturing the electronic device shown in FIG. 1.

FIG. 6 is a cross-sectional view illustrating the example of the methodfor manufacturing the electronic device shown in FIG. 1.

FIG. 7 is a cross-sectional view illustrating the example of the methodfor manufacturing the electronic device shown in FIG. 1.

FIG. 8 is a cross-sectional view illustrating the example of the methodfor manufacturing the electronic device shown in FIG. 1.

FIG. 9 is a cross-sectional view illustrating the example of the methodfor manufacturing the electronic device shown in FIG. 1.

FIG. 10 is a cross-sectional view illustrating the example of the methodfor manufacturing the electronic device shown in FIG. 1.

FIG. 11 is a cross-sectional view illustrating the example of the methodfor manufacturing the electronic device shown in FIG. 1.

FIG. 12 is a cross-sectional view illustrating the example of the methodfor manufacturing the electronic device shown in FIG. 1.

FIG. 13 is a cross-sectional view illustrating the example of the methodfor manufacturing the electronic device shown in FIG. 1.

FIG. 14 is a cross-sectional view of an electronic device according to asecond embodiment of the present invention.

FIG. 15 is a cross-sectional view of the electronic device shown in FIG.14.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bespecifically described with reference to the drawings.

FIGS. 1 to 3 show an electronic device according to a first embodimentof the present invention. The electronic device A1 according to thepresent embodiment includes a substrate 1, an insulating layer 2, aconductive layer 3, a plurality of columnar conductors 4, a plurality ofelectrode pads 51, a sealing resin 6, and an electronic element 71. FIG.1 is a plan view of the electronic device A1. FIG. 2 is across-sectional view along line II-II in FIG. 1. FIG. 3 is across-sectional view along line III-III in FIG. 1.

The substrate 1 is made of a single-crystal semiconductor material. Inthe present embodiment, the substrate 1 is made of single-crystalsilicon (Si). However, the material of the substrate 1 is not limited toSi and may for example be silicon carbide (SiC). The substrate 1 has athickness of about 200 to 550 μm, for example. The electronic element 71is mounted on the substrate 1.

The substrate 1 has an obverse surface 111 and a reverse surface 112.

The obverse surface 111 faces one side in a direction of the thicknessof the substrate 1 (hereinafter, simply the “thickness direction”). Theobverse surface 111 is flat and perpendicular to the thicknessdirection. The obverse surface 111 is either a (100) surface or a (110)surface. In the present embodiment, the obverse surface 111 is a (100)surface. In the present embodiment, the obverse surface 111 has a shapeof a rectangular ring.

The reverse surface 112 faces the opposite side in the thicknessdirection. In other words, the reverse surface 112 faces away from theobverse surface 111. The reverse surface 112 is flat and perpendicularto the thickness direction.

The substrate 1 has an element-receiving recess 14.

The element-receiving recess 14 is recessed from the obverse surface111. The electronic element 71 is disposed within the element-receivingrecess 14. The element-receiving recess 14 has a depth (a separationdistance in the thickness direction between the obverse surface 111 anda recess bottom surface 142, which will be described later) of about 100to 300 μm, for example. The element-receiving recess 14 is rectangularas seen in the thickness direction. This shape of the element-receivingrecess 14 is determined by the obverse surface 111 being a (100)surface.

The element-receiving recess 14 has recess lateral surfaces 141 and therecess bottom surface 142.

The recess bottom surface 142 and the obverse surface 111 face the sameside in the thickness direction. The recess bottom surface 142 isrectangular as seen in the thickness direction. The electronic element71 is disposed on the recess bottom surface 142. The recess bottomsurface 142 is perpendicular to the thickness direction.

The recess lateral surfaces 141 upstand from the recess bottom surface142. The recess lateral surfaces 141 are continuous with the recessbottom surface 142. The recess lateral surfaces 141 are inclinedrelative to the thickness direction. Each recess lateral surface 141forms an angle of 55° with a plane perpendicular to the thicknessdirection. This angle results from the obverse surface 111 being a (100)surface. The element-receiving recess 14 has four recess lateralsurfaces 141 each of which is a flat surface. The recess lateralsurfaces 141 are continuous with the obverse surface 111.

The insulating layer 2 is sandwiched between the conductive layer 3 andthe substrate 1. The insulating layer 2 has a thickness of about 0.1 to1.0 μm, for example. The insulating layer 2 is made for example ofsilicon dioxide (SiO2) or silicon mononitride (SiN).

The insulating layer 2 has a recess-surface insulating region 21, anobverse-surface insulating region 22, and a rear-surface insulatingregion 24.

The recess-surface insulating region 21 is located on theelement-receiving recess 14 of the substrate 1. In the presentembodiment, the recess-surface insulating region 21 covers all of therecess lateral surfaces 141 and the recess bottom surface 142. Therecess-surface insulating region 21 is formed by thermal oxidation, forexample. The recess-surface insulating region 21 is made of SiO₂, forexample.

At least a portion of the obverse-surface insulating region 22 islocated on the obverse surface 111 of the substrate 1. Theobverse-surface insulating region 22 is formed by thermal oxidation. Theobverse-surface insulating region 22 is made of SiO₂, for example. Inthe present embodiment, the obverse-surface insulating region 22 coversthe entire obverse surface 111.

At least a portion of the rear-surface insulating region 24 is locatedon the reverse surface 112 of the substrate 1. The rear-surfaceinsulating region 24 is formed by thermal oxidation. The rear-surfaceinsulating region 24 is made of SiO₂, for example. In the presentembodiment, the rear-surface insulating region 24 covers the entirereverse surface 112.

The conductive layer 3 is electrically connected to the electronicelement 71. The conductive layer 3 forms a conductive path through whichof electrical current flows into and out of the electronic element 71.The conductive layer 3 is located on the obverse surface 111, the recesslateral surfaces 141, and the recess bottom surface 142.

The conductive layer 3 includes a seed layer and a plating layer.

The seed layer is an undercoat for forming a desired plating layer. Theseed layer is sandwiched between the substrate 1 and the plating layer.The seed layer is made of copper (Cu), for example. The seed layer isdeposited by sputtering to a thickness of, for example, 1 μm or less.

The plating layer is formed by electroplating using the seed layer. Inone example, the plating layer is a stack of a Cu or titanium (Ti)layer, a nickel (Ni) layer, and a Cu layer. The plating layer has athickness of about 3 to 10 μm, for example. The plating layer is thickerthan the seed layer.

The conductive layer 3 has pad regions 33, obverse-surface contactingregions 381, and recess-surface contacting regions 382.

The pad regions 33 are located inside the element-receiving recess 14,typically on the recess bottom surface 142. The pad regions 33 locatedon the recess bottom surface 142 are used in mounting the electronicelement 71 on the recess bottom surface 142.

The obverse-surface contacting regions 381 are supported on the obversesurface 111 and each have a portion layered on the obverse-surfaceinsulating region 22 of the insulating layer 2.

The recess-surface contacting regions 382 are supported on the recesslateral surfaces 141 and each has a portion layered on therecess-surface insulating region 21 of the insulating layer 2.

The electronic element 71 is mounted on the recess bottom surface 142.One example of the electronic element 71 is an integrated circuitelement. Other examples of the electronic element 71 include passiveelements such as inductor and capacitor. In the present embodiment, theelectronic element 71 protrudes beyond the obverse surface 111 in thethickness direction.

The sealing resin 6 fills the element-receiving recess 14 at leastpartially and covers the obverse surface 111 at least partially. In thepresent embodiment, the sealing resin 6 fully fills theelement-receiving recess 14. In addition, the sealing resin 6 fullyencapsulates the electronic element 71. In addition, the sealing resin 6reaches the entire outer periphery of the obverse surface 111 as seen inthe thickness direction, covering the obverse surface 111 substantiallyentirely.

The sealing resin 6 has a resin obverse surface 63 that faces in thesame direction as the obverse surface 111. The sealing resin 6 has aplurality of through holes 64. The respective through holes 64accommodate the columnar conductors 4.

Examples of a material of the sealing resin 6 include an epoxy resin, aphenolic resin, a polyimide resin, a polybenzoxazole (PBO) resin, and asilicone resin. Although the sealing resin 6 may be made of either alight transmitting resin or a non-light transmitting resin, a non-lighttransmitting resin is preferred in the present embodiment.

The respective columnar conductors 4 are electrically connected to theobverse-surface contacting region 381 of the conductive layer 3 andexposed from the sealing resin 6 at a side facing away from the obversesurface 111. In the present embodiment, the columnar conductors 4 arelocated directly on the obverse-surface contacting regions 381. Thecolumnar conductors 4 are made of metal. Preferably, the columnarconductors 4 are made of Cu. The columnar conductors 4 are formed byplating. In the present embodiment, the columnar conductors 4 have ashape of a circular column. The columnar conductors 4 may be designed tohave any height. In one example, the height of the columnar conductors 4is from 50 to 440 μm.

The columnar conductors 4 have a conductor obverse surface 41. Theconductor obverse surface 41 is exposed from the sealing resin 6 andfaces in the same direction as the obverse surface 111. In the presentembodiment, the conductor obverse surface 41 is flush with the resinobverse surface 63.

The electrode pads 51 are each disposed in contact with the conductorobverse surface 41 of the corresponding columnar conductor 4. Theelectrode pads 51 are electrically connected to the electronic element71. The electrode pads 51 may be a stack of a Ni layer, a palladium (Pd)layer, and a gold (Au) layer in order from the one closer to theconductor obverse surface 41. In the present embodiment, the electrodepads 51 are rectangular. As seen in the thickness direction, eachelectrode pad 51 overlaps with the obverse-surface contacting region 381at least partially and also with the resin obverse surface 63 at leastpartially. In the present embodiment, the electrode pad 51 encompassesthe columnar conductor 4.

Next, a method for manufacturing the electronic device A1 will bedescribed with reference to FIGS. 4 to 13.

First, a substrate 1 is prepared as shown in FIG. 4. The substrate 1 ismade of a single-crystal semiconductor material. In the presentembodiment, the substrate 1 is made of Si single crystal. The substrate1 has a thickness of about 200 to 550 μm, for example. The substrate 1prepared herein is of a size sufficient for a plurality of substrates 1of the electronic device A1 described above. The manufacturing stepsdescribed below are of a method for collectively manufacturing aplurality of electronic devices A1. While a method for manufacturing oneelectronic device A1 is possible, a method for manufacturing a pluralityof electronic devices A1 at once is practical in view of industrialefficiency. Although the substrate 1 shown in FIG. 4 is not preciselyidentical to the substrate 1 of the electronic device A1, both thesubstrates are generally referred to as the “substrate 1” forconvenience.

The substrate 1 has an obverse surface 111 and a reverse surface 112facing away from each other. In the present embodiment, the obversesurface 111 is a (100) surface, which is a surface having a crystalorientation of (100).

Next, the obverse surface 111 is oxidized to form a mask layer made ofSiO₂. The mask layer has a thickness of about 0.7 to 1.0 μm, forexample.

Next, the mask layer is patterned by for example etching. Through thepatterning, an opening having for example a rectangular shape is formedin the mask layer. The shape and size of the opening is determined inaccordance with the shape and size of an element-receiving recess 14 tobe ultimately produced.

Next, the substrate 1 is subjected to anisotropic etching using, forexample, potassium hydroxide (KOH). KOH is an example of an alkalineetching solution appropriately usable for anisotropic etching of Sisingle crystal. Through the etching, a recess is formed in the substrate1. The recess has a bottom surface and lateral surfaces. The bottomsurface is at a right angle to the thickness direction. The lateralsurfaces form an angle of about 55° with a plane perpendicular to thethickness direction. Through the etching, the element-receiving recess14 shown in FIG. 5 is formed. The element-receiving recess 14 has recesslateral surfaces 141 and a recess bottom surface 142 that is recessedfrom the obverse surface 111. The element-receiving recess 14 isrectangular as seen in the thickness direction.

Next, as shown in FIG. 6, thermal oxidation is performed to form aninsulating layer 2 on the obverse surface 111, the recess lateralsurfaces 141, the recess bottom surface 142, and the reverse surface112. The recess-surface insulating region 21, the obverse-surfaceinsulating region 22, and the rear-surface insulating region 24described above are part of the insulating layer 2.

Next, a seed layer and a plating layer are formed in order to form aconductive layer 3 as shown in FIG. 7. The seed layer is formed bypatterning a layer deposited by for example Cu sputtering. The platinglayer is formed by electroplating using the seed layer. As a result, astack of, for example, a Cu or Ti layer, a Ni layer, and a Cu layer isformed as the plating layer. The seed layer and the plating layer arelayered to form a conductive layer 3. The conductive layer 3 thus formedhas pad regions 33, obverse-surface contacting regions 381, andrecess-surface contacting regions 382.

Next, an electronic element 71 is mounted in the element-receivingrecess 14 as shown in FIG. 8. Specifically, the electronic element 71 ismounted on the recess bottom surface 142. The electronic element 71 isprovided, for example, with solder balls in advance. The solder ballsare coated with flux. With the aid of the flux, which is viscous, theelectronic element 71 is placed on the pad regions 33. The solder ballsare melted in a reflow furnace and then hardened. This completes themounting of the electronic element 71. Instead of solder balls, solderpaste may be applied to the pad regions 33 of the conductive layer 3.The electronic element 71 thus mounted has a portion protruding beyondthe obverse surface 111.

Next, a resist layer 67 is formed as shown in FIG. 9. The resist layer67 is formed from a resist resin material that is highly permeable andcapable of being patterned by exposure to light. The resist resinmaterial is supplied to fill the element-receiving recess 14 andsubsequently to cover the electronic element 71 sufficiently. Then, theresist resin material is patterned by exposure to light so as to form aplurality of through holes 68. The respective through holes 68 reach theobverse-surface contacting regions 381. In the present embodiment, thethrough holes 68 have a shape of a circular column. In addition, thethrough holes 68 have a depth of 50 to 440 μm, for example.

Next, a plurality of columnar conductors 4 are formed as shown in FIG.10. The plurality of columnar conductors 4 are formed by filling thethrough holes 68 with metal such as Cu, by electroplating using theexposed portions of the obverse-surface contacting regions 381 throughthe through holes 68.

Next, the resist layer 67 is removed as shown in FIG. 11, leaving theplurality of columnar conductors 4 upright on the obverse surface 111.

Next, a sealing resin 6 is formed as shown in FIG. 12. The sealing resin6 is formed from a highly-permeable and photocurable resin material. Theresin material is supplied to fill the element-receiving recess 14 andsubsequently to cover the electronic element 71 completely. The resinmaterial is then cured to form the sealing resin 6.

Next, the sealing resin 6 in the state shown in FIG. 12 is ground toremove an upper portion such that each columnar conductor 4 is partiallyexposed. Specifically, the upper portion of the sealing resin 6 shown inFIG. 12 is removed together with the upper portions of the columnarconductors 4 shown in FIG. 12. This defines a resin obverse surface 63of the sealing resin 6 and a conductor obverse surface 41 of eachcolumnar conductor 4. The resin obverse surface 63 and the conductorobverse surfaces 41 are flush with each other. Since the sealing resin 6before the grinding fully covered the columnar conductors 4, the sealingresin 6 after the grinding is provided with the plurality of throughholes 64 each of which accommodates the corresponding columnar conductor4.

Subsequently, electrode pads 51 are formed. The electrode pads 51 areformed by electroless plating with metal such as Ni, Pd, or Au.

The substrate 1 is then cut with, for example, a dicer into individualelectronic devices A1 as shown in FIG. 1-3.

The following describes operation of the electronic device A1.

According to the present embodiment, the sealing resin 6 and thecolumnar conductors 4 protrude beyond the obverse surface 111 of thesubstrate 1. From the standpoint of protection of the electronic element71 and manufacturing convenience, the element-receiving recess 14 isoften associated with restrictions on the dimensions such as a depth. Inaddition, there are various user's requests as to the overall size ofthe electronic device A1 (especially, dimensions in terms of thethickness direction) regardless of the size of the electronic element71. The thickness dimensions of the sealing resin 6 and the columnarconductors 4 can be altered in view of the requests, allowing thethickness dimensions of the overall electronic device A1 to bedetermined more flexibly without a change to the size of theelement-receiving recess 14 and/or the arrangement of the electronicelement 71.

In the process of collectively manufacturing a plurality of electronicdevices A1, the sealing resin 6 initially formed has a larger surfacearea than in the process of manufacturing one electronic device A1.Portions of the sealing resin 6 are received within the plurality ofelement-receiving recesses 14. This is effective to resist a forcetending to displace the sealing resin 6 from the substrate 1. Inaddition, this resisting force may be produced by the substrate 1,preventing the generation of unnecessary stress to solder 331 bondingthe electronic element 71. The individual electronic devices A1 are alsocapable of preventing displacement or detachment of the sealing resin 6from the substrate 1.

The conductor obverse surface 41 of the columnar conductor 4 being flushwith the resin obverse surface 63 of the sealing resin 6 facilitatesappropriate production of the electrode pads 51.

With the electronic element 71 protruding beyond the obverse surface111, the electronic element 71 has a portion located in a protrudingportion of the sealing resin 6 beyond the obverse surface 111. Thisconfiguration may serve to improve the bonding strength between thesubstrate 1, the electronic element 71, and the sealing resin 6.

In the present embodiment, the recess lateral surfaces 141 are inclinedrelative to the thickness direction. This configuration facilitates therecess lateral surfaces 141 to be formed relatively flat. This allowsfor greater ease in forming the seed layer (i.e., the conductive layer3).

FIGS. 14 and 15 show an electronic device according to a secondembodiment of the present invention. The electronic device A2 accordingto the present embodiment includes a substrate 1, an insulating layer 2,a conductive layer 3, a plurality of columnar conductors 4, a pluralityof electrode pads 51, a sealing resin 6, and an electronic element 71.

The substrate 1 is made of a single-crystal semiconductor material. Inthe present embodiment, the substrate 1 is made of single-crystal Si.However, the material of the substrate 1 is not limited to Si and mayfor example be SiC. The substrate 1 has a thickness of about 200 to 550μm, for example. The electronic element 71 is mounted on the substrate1.

The substrate 1 has an obverse surface 111 and a reverse surface 112.

The obverse surface 111 faces one side in the thickness direction. Theobverse surface 111 is flat and perpendicular to the thicknessdirection. The obverse surface 111 is either a (100) surface or a (110)surface. In the present embodiment, the obverse surface 111 is a (100)surface. In the present embodiment, the obverse surface 111 has a shapeof a rectangular ring.

The reverse surface 112 faces the opposite side in the thicknessdirection. In other words, the reverse surface 112 faces away from theobverse surface 111. The reverse surface 112 is flat and perpendicularto the thickness direction.

The substrate 1 has an element-receiving recess 14.

The element-receiving recess 14 is recessed from the obverse surface111. The electronic element 71 is disposed within the element-receivingrecess 14. The element-receiving recess 14 has a depth (a separationdistance in the thickness direction between the obverse surface 111 anda recess bottom surface 142, which will be described later) of about 100to 300 μm, for example. The element-receiving recess 14 is rectangularas seen in the thickness direction. This shape of the element-receivingrecess 14 is determined by the obverse surface 111 being a (100)surface.

The element-receiving recess 14 has recess lateral surfaces 141 and therecess bottom surface 142.

The recess bottom surface 142 and the obverse surface 111 face the sameside in the thickness direction. The recess bottom surface 142 isrectangular as seen in the thickness direction. The electronic element71 is disposed on the recess bottom surface 142. The recess bottomsurface 142 is perpendicular to the thickness direction.

The recess lateral surfaces 141 upstand from the recess bottom surface142. The recess lateral surfaces 141 are continuous with the recessbottom surface 142. The recess lateral surfaces 141 are inclinedrelative to the thickness direction. Each recess lateral surface 141forms an angle of 55° with a plane perpendicular to the thicknessdirection. This angle results from the obverse surface 111 being a (100)surface. The element-receiving recess 14 has four recess lateralsurfaces 141 each of which is a flat surface. The recess lateralsurfaces 141 are continuous with the obverse surface 111.

The insulating layer 2 is sandwiched between the conductive layer 3 andthe substrate 1. The insulating layer 2 has a thickness of about 0.1 to1.0 μm, for example. The insulating layer 2 is made for example of SiO₂or SiN.

The insulating layer 2 has a recess-surface insulating region 21, anobverse-surface insulating region 22, and a rear-surface insulatingregion 24.

The recess-surface insulating region 21 is located on theelement-receiving recess 14 of the substrate 1. In the presentembodiment, the recess-surface insulating region 21 covers all of therecess lateral surfaces 141 and the recess bottom surface 142. Therecess-surface insulating region 21 is formed by thermal oxidation, forexample. The recess-surface insulating region 21 is made of SiO₂, forexample.

At least a portion of the obverse-surface insulating region 22 islocated on the obverse surface 111 of the substrate 1. Theobverse-surface insulating region 22 is formed by thermal oxidation. Theobverse-surface insulating region 22 is made of SiO₂, for example. Inthe present embodiment, the obverse-surface insulating region 22 coversthe entire obverse surface 111.

At least a portion of the rear-surface insulating region 24 is locatedon the reverse surface 112 of the substrate 1. The rear-surfaceinsulating region 24 is formed by thermal oxidation. The rear-surfaceinsulating region 24 is made of SiO₂, for example. In the presentembodiment, the rear-surface insulating region 24 covers the entirereverse surface 112.

The conductive layer 3 is electrically connected to the electronicelement 71. The conductive layer 3 forms a conductive path through whichof electrical current flows into and out of the electronic element 71.The conductive layer 3 is located on the obverse surface 111, the recesslateral surfaces 141, and the recess bottom surface 142.

The conductive layer 3 includes a seed layer and a plating layer.

The seed layer is an undercoat for forming a desired plating layer. Theseed layer is sandwiched between the substrate 1 and the plating layer.The seed layer is made of copper, for example. The seed layer isdeposited by sputtering to a thickness of, for example, 1 μm or less.

The plating layer is formed by electroplating using the seed layer. Inone example, the plating layer is a stack of a Cu or Ti layer, a Nilayer, and a Cu layer. The plating layer has a thickness of about 3 to10 μm, for example. The plating layer is thicker than the seed layer.

The conductive layer 3 has pad regions 33, obverse-surface contactingregions 381, and recess-surface contacting regions 382.

The pad regions 33 are located inside the element-receiving recess 14,typically on the recess bottom surface 142. The pad regions 33 locatedon the recess bottom surface 142 are used in mounting the electronicelement 71 on the recess bottom surface 142.

The obverse-surface contacting regions 381 are supported on the obversesurface 111 and each have a portion layered on the obverse-surfaceinsulating region 22 of the insulating layer 2.

The recess-surface contacting regions 382 are supported on the recesslateral surfaces 141 and each has a portion layered on therecess-surface insulating region 21 of the insulating layer 2.

The electronic element 71 is mounted on the recess bottom surface 142.One example of the electronic element is an integrated circuit element.Other examples of the electronic element 71 include passive elementssuch as inductor and capacitor. In the present embodiment, theelectronic element 71 does not protrude beyond the obverse surface 111in the thickness direction and the entire electronic element 71 isaccommodated completely within the element-receiving recess 14.

The sealing resin 6 fills the element-receiving recess 14 at leastpartially and covers the obverse surface 111 at least partially. In thepresent embodiment, the sealing resin 6 fully fills theelement-receiving recess 14. In addition, the sealing resin 6 fullyencapsulates the electronic element 71. In addition, the sealing resin 6reaches the entire outer periphery of the obverse surface 111 as seen inthe thickness direction, covering the obverse surface 111 substantiallyentirely.

The sealing resin 6 has a resin obverse surface 63 that faces in thesame direction as the obverse surface 111. The sealing resin 6 has aplurality of through holes 64. The respective through holes 64accommodate the columnar conductors 4.

Examples of a material of the sealing resin 6 include an epoxy resin, aphenolic resin, a polyimide resin, a PBO resin, and a silicone resin.Although the sealing resin 6 may be made of either a light transmittingresin or a non-light transmitting resin, a non-light transmitting resinis preferred in the present embodiment.

The respective columnar conductors 4 are electrically connected to theobverse-surface contacting region 381 of the conductive layer 3 andexposed from the sealing resin 6 at a side facing away from the obversesurface 111. In the present embodiment, the columnar conductors 4 arelocated directly on the obverse-surface contacting regions 381. Thecolumnar conductors 4 are made of metal. Preferably, the columnarconductors 4 are made of Cu. The columnar conductors 4 are formed byplating. In the present embodiment, the columnar conductors 4 have ashape of a circular column. The columnar conductors 4 may be designed tohave any height. In one example, the height of the columnar conductors 4is from 50 to 440 μm. The columnar conductors 4 have a conductor obversesurface 41. The conductor obverse surface 41 is exposed from the sealingresin 6 and faces in the same direction as the obverse surface 111. Inthe present embodiment, the conductor obverse surface 41 is flush withthe resin obverse surface 63.

The electrode pads 51 are each disposed in contact with the conductorobverse surface 41 of the corresponding columnar conductor 4. Theelectrode pads 51 are electrically connected to the electronic element71. The electrode pads 51 may be a stack of a Ni layer, a Pd layer, anda Au layer in order from the one closer to the conductor obverse surface41. In the present embodiment, the electrode pads 51 are rectangular. Asseen in the thickness direction, each electrode pad 51 overlaps with theobverse-surface contacting region 381 at least partially and also withthe resin obverse surface 63 at least partially. In the presentembodiment, the electrode pad 51 completely covers the columnarconductor 4.

The following describes operation of the electronic device A2.

According to the present embodiment, the sealing resin 6 and thecolumnar conductors 4 protrude beyond the obverse surface 111 of thesubstrate 1. From the standpoint of protection of the electronic element71 and manufacturing convenience, the element-receiving recess 14 isoften associated with restrictions on the dimensions such as a depth. Inaddition, there are various user's requests as to the overall size ofthe electronic device A2 (especially, dimensions in terms of thethickness direction) regardless of the size of the electronic element71. The thickness dimensions of the sealing resin 6 and the columnarconductors 4 can be altered in view of the requests, allowing thethickness dimensions of the overall electronic device A2 to bedetermined more flexibly without a change to the size of theelement-receiving recess 14 and/or the arrangement of the electronicelement 71.

In the process of collectively manufacturing a plurality of electronicdevices A2, the sealing resin 6 initially formed has a larger surfacearea than in the process of manufacturing one electronic device A2.Portions of the sealing resin 6 are received within the plurality ofelement-receiving recesses 14. This is effective to resist a forcetending to displace the sealing resin 6 from the substrate 1. Inaddition, this resisting force may be produced by the substrate 1,preventing the generation of unnecessary stress to solder 331 bondingthe electronic element 71. The individual electronic devices A2 are alsocapable of preventing displacement or detachment of the sealing resin 6from the substrate 1.

The conductor obverse surface 41 of the columnar conductor 4 being flushwith the resin obverse surface 63 of the sealing resin 6 facilitatesappropriate production of the electrode pads 51.

In the present embodiment, the recess lateral surfaces 141 are inclinedrelative to the thickness direction. This configuration facilitates therecess lateral surfaces 141 to be formed relatively flat. This allowsfor greater ease in forming the seed layer (i.e., the conductive layer3).

Electronic devices according to the present invention are not limited tothe specific embodiments described above. For electronic devicesaccording to the present invention, various changes and alterations maybe made to specific configuration of component elements.

The invention claimed is:
 1. An electronic device, comprising: asubstrate made of a semiconductor material and having a substrateobverse surface and a substrate reverse surface that are opposite toeach other in a thickness direction of the substrate; an electronicelement mounted on the substrate; a conductive layer electricallyconnected to the electronic element; a sealing resin; and a columnarconductor, wherein the substrate is formed with an element-receivingrecess recessed from the substrate obverse surface and having a recessbottom surface, the electronic element is mounted on the recess bottomsurface, the conductive layer has an obverse-surface contacting regionlocated on the substrate obverse surface, the sealing resin is disposedin at least a part of the element-receiving recess and covers at least apart of the substrate obverse surface, the columnar conductor iselectrically connected to the obverse-surface contacting region of theconductive layer and exposed from the sealing resin at a side oppositeto the substrate obverse surface, and an obverse surface of theelectronic element is spaced further from the recess bottom surface inthe thickness direction than an obverse surface of the obverse-surfacecontacting region of the conductive layer, wherein the columnarconductor has a side surface that is parallel to the thickness directionand covered with the sealing resin; and an electrode pad that is incontact with the columnar conductor at a side of the columnar conductorthat is opposite to a side facing the substrate obverse surface, whereinthe columnar conductor and the electrode pad are made of mutuallydifferent electroconductive materials.
 2. The electronic deviceaccording to claim 1, wherein the columnar conductor has a conductorobverse surface that is exposed from the sealing resin and faces in asame direction as the substrate obverse surface.
 3. The electronicdevice according to claim 2, wherein the sealing resin has a resinobverse surface facing in the same direction as the substrate obversesurface, and the conductor obverse surface is flush with the resinobverse surface.
 4. The electronic device according to claim 3, whereinan entirety of the element-receiving recess is filled with the sealingresin.
 5. The electronic device according to claim 4, wherein thesealing resin reaches an entire periphery of the substrate obversesurface as seen in the thickness direction.
 6. The electronic deviceaccording to claim 1, wherein the columnar conductor is made of a metal.7. The electronic device according to claim 6, wherein the columnarconductor is made of Cu.
 8. The electronic device according to claim 6,wherein the columnar conductor is formed by plating.
 9. The electronicdevice according to claim 1, further comprising an electrode pad that isin contact with the columnar conductor at a side opposite to thesubstrate obverse surface.
 10. The electronic device according to claim9, wherein the electrode pad overlaps with at least a part of each ofthe columnar conductor and the sealing resin as seen in the thicknessdirection.
 11. The electronic device according to claim 10, wherein theelectrode pad encompasses the columnar conductor as seen in thethickness direction.
 12. The electronic device according to claim 1,wherein the sealing resin encapsulates the electronic element.
 13. Theelectronic device according to claim 1, wherein the conductive layer hasa pad region that is located on the recess bottom surface and used formounting the electronic element.
 14. The electronic device according toclaim 13, wherein the element-receiving recess has a recess lateralsurface extending upwards from the recess bottom surface.
 15. Theelectronic device according to claim 14, wherein the conductive layerhas a recess-surface contacting region located on the recess lateralsurface.
 16. The electronic device according to claim 15, wherein therecess lateral surface is continuous with the recess bottom surface. 17.The electronic device according to claim 16, wherein the recess lateralsurface is continuous with the substrate obverse surface.
 18. Theelectronic device according to claim 17, wherein the recess-surfacecontacting region is continuous with the obverse-surface contactingregion.
 19. The electronic device according to claim 13, wherein thesubstrate is made of a single-crystal semiconductor material.
 20. Theelectronic device according to claim 19, wherein the semiconductormaterial is Si.
 21. The electronic device according to claim 20, whereinthe substrate obverse surface and the substrate reverse surface are eachflat and perpendicular to the thickness direction.
 22. The electronicdevice according to claim 21, wherein the substrate obverse surface is a(100) surface.
 23. The electronic device according to claim 22, whereinthe recess lateral surface forms an angle of 55° with the recess bottomsurface.